JWST Catches New Asteroid Belt Forming Around Nearby Star

Fomalhaut is the brightest star in the constellation of the Southern Fish and it is the second brightest in the sky when it comes to having a planetary system around it (after Pollux). But the Fomalhaut system is still a "work in progress" – it’s unsure if it has planets but what it certainly does have is a lot of stuff going on. Collisions, clouds, and a wide belt like Sun’s own Kuiper Belt have been spotted before. A new asteroid belt has now been announced.

By using JWST's mid-infrared instrument (MIRI), researchers have been able to resolve the inner disk of debris around Fomalhaut. This star is 25 light-years from Earth and about 440 million years old so we are looking at the formative years of this system. The team knew that there was dust and pebbles in the inner disk but they didn’t know exactly if this was equivalent to the asteroid belt in the Solar System.

“We assumed it to be an almost identical analog to our Solar System's asteroid belt; it turns out the truth is a bit different,” lead author Dr András Gáspár, from The University of Arizona, Tucson, told IFLScience. “While the inner edge of the warm disk component is located at a thermally equivalent region, it extends much further out. In addition, we resolved a secondary gap in the system, which is very intriguing, as it hints at the presence of an ice-giant planet in the system at a thermally equivalent distance as Neptune is in our solar system.”

The new observations suggest that there is a misalignment between this disk and the Kuiper-belt-like one located further out. There are also dust clouds. One was previously mistaken for a planet and this work reports a second one which they call the "great dust cloud". It is believed that planets are already formed around this system but there are also a lot of planetesimals around.

It is an active system and small perturbations by the planets onto the belt of debris can lead to collisional cascades. And then a dust cloud is born. It is possible that the Solar System underwent a similar period of messy activity. There are certainly similarities.

“We are just starting to unravel the system. It seems that the planetary system is still not settled dynamically. The inner terrestrial planet zone is still a mystery. The outer regions seem to be familiar though, with many analogs to the observable properties of the solar system,” Dr Gáspár explained to IFLScience.

While the system is providing insights into the early solar system, Fomalhaut is very different from the Sun. It’s a much brighter and hotter star, meaning that it will burn through its nuclear fuel more quickly. It has lived about a third of its life already. It has about one billion years left before it turns into a red giant.

“By the time this planetary system settles down and possibly enables life to flourish, the central star will have already burned through its nuclear fuel and ended its life,” Dr Gáspár told IFLScience.

The research is published in Nature Astronomy.